Polyimide coating process and material

Abstract

A protective layer composition, suitable for protecting metal electrodes on components and other microelectronic circuitry, comprises an organic thermoplastic polymeric material, an organic solvent or solvents, and a non-ionic fluorocarbon surfactant as a wetting/leveling/flow control agent. A typical formulation comprises an aromatic polymer which cures to form a polyamide-imide polymer, an organic solvent or a mixture of orangic solvents and a non-ionic fluorocarbon surfactant.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent is: 
     
       1. A process for forming a seal coating on electronic circuitry comprising: applying to said circuitry a filler free coating material which includes: an aromatic polymer which, when cured, forms a polyimide,   an organic solvent for said polymer, and   a non-ionic fluorocarbon surfactant, and curing the material to form a polyimide seal coating on said circuitry.     
     
     
       2. The process of claim 1 wherein the aromatic polymer is selected from the group consisting of a polyamic acid and a polyamic acid-imide. 
     
     
       3. The process of claim 1 wherein the layer includes from about 0 to 1% by weight of a silane adhesion promoter. 
     
     
       4. The process of claim 1 wherein the coating material includes by weight: about 2 to 20% polymer, about 0.001 to 1.0% surfactant and about 80 to 90% solvent. 
     
     
       5. The process of claim 4 wherein the coating material includes by weight about 4 to 8% polymer, about 0.001 to 1% surfactant and about 92 to 96% solvent. 
     
     
       6. The process of claim 1 wherein the fluorocarbon surfactant is selected from the group consisting of non-ionic fluoroinated alkyl-ester surfactants represented by the formula: ##STR8## where R f  is a perfluoroalkyl group having from 3 to 12 carbon atoms and m is integer from 2 to 12, and R' is a low molecular weight polyoxethylene, a polyoxypropylene or a polyoxyethylenepolyoxypropylene copolymer group, N-polyoxyethylene substituted perfluorosulfonamides represented by the formula: ##STR9## in which R is a lower alkyl group having from 1 to 6 carbon atoms such as methyl, ethyl propyl, butyl, etc. and n is an integer from 2-30, and N-alkanol perfluoroalkanesulfonamides represented by the formula:   R.sub.f SO.sub.2 N(R')RCH.sub.2 OH     where R f  is a perfluoroalkyl group containing 4 to 12 carbon atoms, R is an alkylene bridging group containing 1 to 12 carbon atoms, and R' is a hydrogen atom or an alkyl group containing 1 to 6 carbon atoms; and the corresponding esters.   
     
     
       7. A process for forming an aromatic seal coating on metal conductor lines on the surface of a substrate and the solder joints and pads forming the connection between the substrate and an integrated circuit chip which is electrically bonded thereto comprising applying to said surface a filler free coating material which comprises 2 to 20% by weight of an aromatic polymer which, when cured, forms a polyimide about 80 to 90% by weight of an organic solvent for said polymer, about 0.001 to 1% by weight of a non-ionic fluorocarbon surfactant, and about 0 to 1% by weight of silane adhesion promoter, and curing material to form a polyimide seal coating.